U.S. Pat. No. 5,082,344 discloses a receptacle for intermating with a push-pull optical fiber connector. The receptacle comprises first and second receptacle members that receive coupling mechanism including a cantilever style catch piece. The coupling mechanism receive a cylindrical slotted alignment sleeve. The first and second receptacle members are ultrasonically joined together to captivate the catch piece and alignment sleeve therein. The alignment sleeve, as captivated, floats with respect to the coupling mechanism within some degree of freedom. With specific reference to FIGS. 1 and 2, there is further known a multiple position embodiment of the receptacle disclosed comprising first and second receptacle members having multiple positions for receiving a plurality of intermating connectors. The receptacle members are ultrasonically welded to captivate a coupling mechanism and an alignment sleeve therebetween. In an embodiment of a multiple position fiber optic receptacle, one side of the receptacle receives a fiber optic connector according to the detailed specification for the proposed standard for an SC style connector, document IEC QC 210X0/002 promulgated by IEC subcommittee no. 86B and dated May 1994. An example of a connector according to the aforementioned standard is the AMP SC fiber optic connector. The opposite side of the receptacle receives a connector carrying multiple fiber optic ferrules.
One critical aspect of fiber optic connector coupling is the proper alignment of fiber cores. It is preferred that the cores in mating ferrules be precisely coaxial when in a mated condition. To that end, it is conventional that fiber optic coupling mechanisms utilize a cylindrical alignment sleeve receiving cylindrical and opposing ferrules terminating optical fibers. For proper coaxial alignment of mating ferrules, the inner diameter of the alignment sleeve is uniform throughout and dimensioned as closely as possible to the outer diameter of the terminated ferrules. It being apparent to one of ordinary skill in the art that in order to insert the ferrule into a precisely dimensioned alignment sleeve, a certain amount of insertion force is necessary to overcome the friction between alignment sleeve and ferrule. It also being apparent to one of ordinary skill in the art that misalignment between the alignment sleeve and ferrule substantially increases the insertion force.
In the case of a multiple position fiber optic connector intermating with a multiple position fiber optic receptacle, the insertion force for each ferrule is additive. Additionally, the manufacturing tolerances associated with the ferrule to ferrule spacing and alignment sleeve to alignment sleeve spacing can cause the axis of a ferrule to the axis of its respective alignment sleeve to be misaligned. In, for example a duplex or four position arrangement, since the alignment sleeve is not rigidly captivated within the receptacle, there is a certain amount of alignment sleeve float with respect to the receptacle. The float between the alignment sleeve and the receptacle is able to accommodate and correct some misalignment as the ferrule makes initial contact with the alignment sleeve guided by a lead-in of the receptacle to urge the axis of the ferrule into coaxial alignment with the axis of the alignment sleeve. Because of the alignment sleeve to receptacle float, a certain amount of misalignment may be accommodated.
As the number of positions in the connector increases, the manufacturing tolerances of the center to center spacing of both ferrule and alignment sleeve add. As misalignment of the center axis of the ferrule to the center axis of the alignment sleeve increases, the capacity of the inherent float of the alignment sleeve in the receptacle to correct any misalignment diminishes. At some point, misalignment may cause any number of problems. Misalignment may increase the insertion force making complete connection of the receptacle and connector difficult. Misalignment may increase the insertion force to a level that can overcome the spring force in one or more of the spring loaded ferrules. If the ferrule spring force is overcome on any individual ferrule, the spring will compress, preventing the ferrule from contacting its mating ferrule. The result is either a misconnection or malconnection of one or more ferrules in the connector. Misconnection or malconnection of one ferrule in a number of ferrules of a connector is a failure mode that may not be immediately apparent. Misalignment may cause the ferrule to exert sufficient force on the alignment sleeve to damage it. Damage may necessitate replacing the entire part.
There is a need, therefore, for a rugged multiple position fiber optic receptacle with improved connectivity at lower insertion forces. There is a further need for a repairable multiple position fiber optic receptacle.